Press for sheet metal



Oct. 20, 1931. c. J. RHODES 1,828,201

PRESS FOR SHEET METAL Filed April 30, 1929 g I I l sten-ted (jet. 20, 193i UETED STATES PATENT OFFICE PRESS FOR SHEET METAL Application filed April 30, 1929, Serial No. 359,307, and in Great Britain February 15, 1929.

This invention relates to improvements in presses for sheet metal, and it has for its object certain improvements designed to secure a more constant pressure of the tool throughout its operation.

According to this invention as applied to a draw-press instead of causing the pressure of the draw-ring to be directly transmitted to the usual pressure plate or table by which the draw-ring is supported, and thence to the rubber buffer or spring, there is interposed between said buffer and the said plate or table a system of toggle levers through which the pressure is transmitted to the buffer in manner such that a constant, or substantially constant, resistance is offered by said butter throughout the drawing opera tion.

In order that the invention may be the better understood drawings are appended in which Fig. l is a front view of a press embodying the present invention.

Fig. 2 is a fragmentary sectional view showing certain details.

Fig. 3 is a section to a larger scale on line B Fig. 2.

Referring to the accompanying drawings in which only such parts of the machine are 31} identified as are necessary for the proper understanding of the invention, 1 indicates the fixed table or support for the lower die 2 and block 2* with which co-operates the usual upper movable die 3. 4 indicates a draw-ring mounted within the die 2 and supported by the pins 5 from the pressure table 6, through which table passes a guide 7 carried by the table 1. Secured to the table 6 are the upper ends of links 8, one disposed on each side of the guide 7, the lower end of each of said links being connected to the longer limbs of a pair of L shaped or hell crank levers 9, which levers their opposite ends are connected to a block secured to the guide 7 for the table Revolubly mounted upon pins 10 passing through the elbows of the levers 9 are rollers 11, said rollers bearing against the upper surface of a thrust plate 12 supported by the butter 13, which latter is supported by the his plate 14 carried by an extension 15 of the guide 7. The plate let is supported by nuts 16 engaging the screw-threaded end of the extension 15, said nuts permitting the initial compression of the butter to be adjusted.

In order to reduce friction at the point of contact of the rollers 11 with the upper surface of thrust plate 12, said plate is recessed as shown, andthe cavity thus formed is filled with a suitable lubricant.

As the draw-ring l is depressed and with it the table 6, thrust is transmitted through the links 8 to the ends of the longer limbs of the levers 9, the lon 'itudinal axes of which are normally located in a plane substantially at 45 to the horizontal, whereby when the thrust is acting to move these levers their effective length progressively increases. From the foregoing it will'be seen that during the descentof the table the gradually increasing reaction of the buffer will be metby the above gradual increase of leverage. In place of rollers 11 slides may be substituted.

Claims.

1. In a press for sheet metal a movable die, a fixed die, a draw ring in said fixed die, a pressure table, for supporting said drawring, a substantially vertically disposed buffer, supported atthe lower end thereof, a body, fixed with relation to said pressure table, a pressure plate, mounted on the top of said bufler and having a recess to hold a lubricant, multiple bell-crank levers, movably connected each atone end thereof to a part on thepressure table and at the other end 5 thereof to said body, and rolls upon said levers, for hearing down upon said pressure plate and operable in said recess and in said lubricant, thereby compressing said buffer.

2. In a press for sheet metal, a movable die, a fixed die, a draw in said fixed die, a pressure table for supporting said draw ring,

a substantially vertically disposed buffer supported-at the lower end thereof, a pressure receiving member at the upper end of said buffer, a body fixed with relation to said pressure table, multiple bell crank levers movably connected each at one end thereof to a part of said table and at the other end thereof to said body, and parts on said levers for bearing down upon said member, thereb compressing said bufier, said member aving thereon a lubricant holding recess at the surface thereof which contacts with said lever parts, thereby reducing the friction of said parts on said member.

3. In a press for sheet metal, a pressure table, a bufi'er, a thrust plate resting on the top of said buffer, said thrust plate being provided With a recess in its upper face for olding a lubricant, and interpivoted rockable devices interposed between said pressure table and said thrust plate for imparting a direct downward rolling thrust on said thrust plate within the area of said recess and said body of lubricant, when the press is operated.

4. In a press for sheet metal, a fixed table, a uide thereon, a pressure table movable on said guide, a buffer, a thrust plate having a recess for holding a puddle of lubricant and disposed on said buil'er, and interpivoted rockable devices interposed between the said pressure table and said thrust plate for im-- parting a rolling thrust action on said thrust plate at points Within area of said recess and said lubricant, to reduce friction.

5. In a press for sheet metal, in combination, a guide plate; a guide; a block thereon; links pivoted to said guide plate; a buffer on said guide; a thrust plate having a recess in its upper face to hold a lubricant, bell crank leversconnected to said links, to each other and to a block on said guide, thrust rollers on said bell crank levers, said rollers operating within said recess and in said lubricant to reduce friction.

6. In a press for sheet metal, in combination, a fixed support, a guide depending therefrom, a block fixed on said guide, a pressure tablemovable on said guide, a buffer, a thrust plate thereon, said thrust late having a recess in its upper face, a lubricant in said recess, bell crank levers having linked connection with the pressure table, with each other and with said block and rollers on said bell cranks adapted to traverse said thrust plate throu h said lubricant to reduce friction.

7. n a press for sheet metal, a fixed table, a resilient buffer supported thereby, a thrust plate disposed on the top of said bufler, said thrust plate having a recess in its upper face to receive a lubricant, and interpivoted rockable devices having rolling thrusting contact with the said thrust plate at points within the area of said recess and said lubricant to reduce friction.

In testimony whereof I have hereunto set my hand.

CHARLES JOSEPH RHODES. 

